Air separator for fuel pumping apparatus of internal combustion engines



Dec. 12, 1939. w. vorr ET AL 2,183,034 AIR sEPARA'roR FOR FUEL PUMPING APPARATUS'QF INTERNALHCOMBUSTIOR ENGINES 7 Filed June 18, 1937 2 Sha ets-Sheet 1 7675 as as Dec. 12, 1939. w. VOIT El AL 2,183,034

AIR SEPARA'I'OR FOR FUEL PUMPING APPARATUS OF INTERNAL COMBUSTION ENGINES Filed June 18, 1957 2 Sheets-Sheet 2 25 contains fuel to the reservoir that is for the time of each delivery pump 4 closure cocks B are in which there is no flushing of the suction cham- A pendulum 50 adapted to swing about the axis 55 Patented Dec.12,1939 2,183,034

UNITED STATES PATENT OFFICE AIR SEPARATOR FOR FUEL P UMPING AP- PARATUS OF INTERNAL COMBUSTION EN- GINES Willy Voit, Stuttgart-Bad Cannstatt, and Johann Friedrich Janssen, Stuttgart, Germany; assignors to Robert Bosch Gesellschaft mit b'eschriinkter )Blaftung, Stuttgart, Germany Application June 18, 1937, Serial No. 149,038 lin Germany June 22, 1936 5 Claims. (Cl. 183-25) In injection apparatus for internal combustion ber of the injec pu p y the EXCESS of fuel engines such as aircraft engines, a hand-pumping D p apparatus, two delivery pumps and the injec- Figure 4 is a longitudinal section through a tion pump are arranged near the internal comsecond construction.

5 bustion engine, while the reservoirs for the fuel F gu e 518 a P Of a -D p n p ant av- 5 are frequently arranged remotely from the engine. ing two fuel reservoirs. So long as everything is in order, the delivery Figure 6 is a longitudinal section through a pumps deliver considerably more fuel free from third example of construction. bubbles than the injection pumps consume when Figure 7 is a section on the line IIII of Figure 10 adjusted for full load. The excess fuel is, as a 6, in which it is assumed that only very little 10 rule, conveyed back to the suction side of the defuel is contained in the float chamber of the livery pump through a return flow valve adjusted separator. to a predetermined pressure. By the use of an air Figure 8 is a section on the line IIIIII of Fig. separator arranged between the delivery pump 6; it is here assumed that the float chamber of 1:. d th i jection pump, surplus fuel can also the separator is entirely, or almost entirely, filled flow away' through the air discharge pipe. In with fuel. order to prevent separated air passing to the suc- In the drawings l denotes an injection D p, tion side of the delivery pumps, the air discharge which delivers fuel through pressure p p 2 to pipe, through which, as t t also fuel can flow the injection nozzles of an internal combustion away, must here, departing from the rule, be conengine (not ShOWn)- TWO d very pumps 4 are 20 veyed back into the reservoir, for which purpose remotely connected to a fuel 0911138111181 3, and a long return pipe is necessary in many plants. draw fuel by means of the pivoted p p 311 from Where several fuel reservoirs are provided, the the container and i through the delivery conveying back of the separated air which still Pipe 5 to an air separator In the suction Pipe arranged, whilst a manually operated pumping device P is provided in the suction pipe of one delivery pump. The air separator 6a is connected to one end of the suction chamber of the injection pump l by a pipe 1, through which fuel freed from air is delivered in excess to this pump. The other end of the suction chamber of the pump 1 is connected to the suction pipes 4a of the delivery pumps 4 by a pipe 8a, through which the being connected to the delivery apparatus is very awkward.

According to the present invention the return pipe to the reservoir for the air separated in the 30 air separator can be entirely dispensed with, if

a float is arranged in the air separator, which float is arranged in an air-separating chamber,

and by the float action that it experiences on immersion in the fuel reaching the chamber causes excess fuel not taken up by the separate pumps 35 :2 g g the air dls'chasge i ig of the injection apparatus is conveyed back to the e c t r as soon an S0 mg e suction side of the delivery pumps 4. An overflow of m chamber a predetermmed valve 9 in the pipe 8a is adjusted to the desired g s gg ffig fig i 52 3;: g:g pressure in the suction chamble; off the injection pump. An air discharge pipe a rom the sepag zg gr g fig ggzfig gg gfigggi ig i fig rator opens into the induction pipe S of the in- 40 ternal combustion engine. pPsmon of the casing of the chamber that only The cylindrical casing No of the air separator can flow away through the Open plpecomprises a bottom l2, which in the construction Several examples of of the inven' illustrated constitutes one end of the casing, and tion are Shown in the a drawings, in a screwed-0n cover I3 which constitutes the other which! end. In the centre of the boss of the cover a Figure l is a general arrangement of a fuel t d d b re is provided for the pipe union l4 pump plant provided with an air separator'and of the air discharge pipe Illa, and below it for having e c s delivery through the Suction Chamthe union I8 of the fuel feed pipe 5 leading from her of the injectifln D P- the delivery pumps 4 to the separator. In the Figure 2 s a longitudinal Section o h the centre of a boss on the base of the casing the pipe first e a p of Construction -'I for the purified fuel is connected to the internal Figure 3 is a diagram of a fuel-pumping plant space of the separator by means of the when l5.

of the casing is mounted in the bosses in the cover and bottom, and in it an annular space 52 closed by the boss of the cover is arranged. This annular space is in communication with the union l8 and the fuel feed pipe 5 and from it a pipe 53 fixed to the rotatable member conveys fuel into the internal space of the casing.

The hub 5| of the pendulum carries a suspended weight 54 on its lower end, whereby the centre of gravity of the pendulum lies below its axis of rotation. A bore or passage 55 starting from the lowest part of the pendulum connects with a longitudinal bore 56, which is always connected by the union I 5 to the pipe I for purified fuel leading to the suction chamber of the fuel pump.

In the cover end of the journal bearing of the rotatable member a longitudinal bore 51 is formed, which through the union I4 communicates at one end with the air discharge pipe Illa and at the other end opens into the interior of the separator through a bore 58 and a radial recess 59 having a thread. A valve piece 50 in which two longitudinal bores 6| and 62 are provided is screwed into the thread of the recess 59. One end of bore BI is in communication with the bore 58. The other end of bore 6| does not extend to the free end of the valve piece, but is in communication with the second bore 62 by a transverse passage 63. The longitudinal bore 62 merges from its contracted mouth 64 at the free end of the valve piece into a conical valve seat 55 and opens at the other end into a face of the valve piece situated at some distance from the socket of the rotatable member. In the bore 62 is a valve-needle 66, which is fixed at its lower end to a float 61 surrounding the valve piece. The float is guided on the valve piece, and together with the valve needle can move radially of the rotatable member. Between the pipe 53 and the float 61 a partition wall 68 is secured to the hub 5| of the rotatable member, and this prevents fuel, entering the separator through the pipe 53, from directly passing to the valve opening 64 at the free end of the valve piece.

In the boss of the cover of the casing a pipe 10 for feeding sealing oil is connected to a bore 59, whilst an oil groove H is provided in the part of the boss surrounding the journal bearing of the rotatable member at this end which groove is in communication with the bore 69. The sealing oil fed under pressure through the pipe 10 prevents fuel passing from the annular space 52 along the journal bearing of the rotatable member to the air discharge pipe lOa.

An air separator of this construction is so arranged according to Figure 1, in the pumping plant of an internal combustion engine that is variable in position, for example an aircraft engine, that in the normal position the am's of displacement of the swinging member of the air separator lies normal to the direction of flight. In upward anddownward movements of the engine, in which the casing of the air separator rocks about its axis which remains horizontal, the pendulum tends to hold the mouth of the discharge bore 55 of the rotatable member always in the lower internal space of the separator that is fllled with fuel freed from air, so that this fuel can pass unhindered to the injection pump. If the fuel in the air separator exceeds a predetermined height, the float 61, and with it the valve needle is raised to such an extent, that the valve needle engages with the conical seat in the valve member, so that the connection between the internal space of the casing of the air separator and the air discharge pipe Illa is interrupted.

If fuel containing air or gas bubbles is fed into the separator, the bubbles collecting for the time being in the upper part of the internal space have a downward pressure action on the level of the fuel. After said level has fallen below a predetermined height the float also sinks whereupon the valve needle opens the conical valve, so that the air can escape to the induction pipe through the discharge pipe containing a throttle. The upward movement of the float must overcome the opposing pressure acting on the valve in the opening direction and also the friction of the needle in the valve member. The throttling of the air being drawn off is necessary, so that the pressure in the air separator may not fall below the pressure desired in the suction chamber of the injection pump.

If, as in the diagram of a fuel-pumping plant shown in Fig. 3, the feature is abandoned of running the fuel delivered in excess through the suction chamber of the injection pump, the excess of fuel pumped by the delivery pumps 4 can be led directly from the pressure side to the suction side of these pumps. The pressure pipe 5 of each of the delivery pumps 4 is connected, in this case, to the suction pipe 4a connected to the fuel reservoir 3 by a pipe 5a, through an overflow valve R adjusted to the delivery pressure of these pumps. Here, only as much fuel flows to the air separator 61) as the injection pump can deal with.

In Figure 4 an example of construction of an air separator for a pumping plant such as shown in Figure 3 is illustrated. A rotatable member 12 is mounted in the centre of the bottom [2 and the cover [3 of a cylindrical casing llb. On the side of the rotatable member facing the casing bottom, an annular space H, open towardsthe bottom of the casing, is arranged in its hub 13, and is closed by this bottom. The annular space is connected, on the one hand, to the feed pipe 5 connected to the casing bottom, and on the other hand, two pipes 15 fixed in the hub of the rotary member lead to the internal space of the casing. The stream of fuel emerging from the free end of these pipes strikes on a baffle-plate 16 secured to the rotatable member, which shuts off the chamber for the feed of the fuel from the rest of the internal space of the casing, and is only open towards the bottom of the casing. The rotatable member carries a pendulum-like weight 11 on the half opposite the pipes 15, by which the centre of gravity of the rotary member is shifted in this direction from the axis of the rotatable member. A bore 18, starting from the lowest part of the pendulum, connects through a longitud nal bore 19 the part of the interior of the casing that is for the time being at the bottom with the discharge pipe 1 for the fuel free from bubbles connected to the bottom of the casing. The air discharge pipe Illa is connected to the centre of the cover l3 of the casing.

On the offset axis 13 of the rotatable member 72 a bush 80 is rotatably mounted, which at one side carries a float BI and opposite thereto a pendulum-like weight 82, by which the weight of the fioat is balanced. A pipe 83 is carried radially to the bush through the body of the float and fastened to the bush. A radial bore 84 connects' the end of the pipe with the bearing surface of the bush. In the same radial plane of this bore in the bush a radial bore 85 is also provided in the axis of the rotatable member, and opens into a longitudinal bore 86 extending up to the rupted, until so pipe. If so during flying in curves or v rotation of the rotatable member adjusts itself end of the axis at the cover side. In the float 8i 2. cross-pipe 81 is arranged parallel to the long axis of the rotatable member, and to this pipe the radial pipe 83 is connected. Contracted parts 88 are provided in the two mouths of the cross pipe 81 carried through the .wall of the float, and inside the cross pipe a ball 89 is arranged which can move freely in this pipe. In the longitudinal bore 89 there is a throttle 99.

A second longitudinal bore 9I is provided in the axis 13 of the rotatable member, and is connected by a radial bore 92 to an annular groove 93 formed in the boss of the cover. The annular groove 93 is connected by bores to a pipe 19 admitting sealing oil. The sealing oil can reach annular grooves 95 that are turned in the periphery of the hub of the rotatable member through several bores starting from-the longitudinal bore 9|. By the sealing oil present in the annular grooves 93 and 95 and which stands under pressure, fuel is prevented from passing to the pipe union I4 and at the same time the running surface of the bush of the float is lubricated.

If the interior of the air separator shown in Fig. 4 is filled with fuel above a predetermined level, the fioat owing to its rise stands in the position shown and holds the annular bush in this position, in which its bore 89 does not coincide with the bore 85 in the rotatable member, so that the pipes 81 and 83 leading to the upper part of the interior nected to the longitudinal bore 89 in the rotatable member and thereby also not to the air discharge much/air collects in the upper part of the internal space that it forces the fuel level more and more downwards, the float sinks with the'fuel level and simultaneously rotates the annular bush also downwards. In this case, the

openings 88 of the cross pipe 81 stand always higher than the level of the fuel, as the float only dips to a small depth in the fuel and does not reach these openings. If the level of the fuel sinks below a predetermined height and the float has turned to such an extent downwards that the bore 89 of the annular bush slides over the bore 85 of the rotary member, the air space in the interior of the casing is connected to the air dischargepipe and the air flows away to the induction pipe of the engine. By the admission of fresh fuel the float is again raised and the annular bush rotated to such an extent that the connection to the air discharge pipe is again intermuch separated. air is again present in the internal space that the opening operation starts afresh. The pressure in the interior of the air separator also in this example of construction cannot sink pressure in the suction chamber of the injection pump on opening the air discharge pipe owing to the throttle 99 provided therein.

If the engine inclines sideways, for instance the like. the axis of obliquely or even perpendicularly to the fuel level in the casing. In these cases, the opening 88 in the cross pipe 81 that is directed downward for the time being is closed by the ball 89, so that no fuel can pass through this opening to the pipe 83 and the annular sleeve. As these positions are only temporarily assured, the controlling of the rotatable member subject to the action of gravity and of the annular bush operated by the rise of the float is only interrupted for a short time. But

even during this time an emergence of fuel through the air discharge is prevented by the of the casing are not con-- to the longitudinal bore below the desiredcross pipe, so that in any desired working position of the engine onlyair free from fuel passes out of the air separator.

. In the fuel-pumping plant shown in Fig. 5 two fuel reservoirs 3 are provided, one of which is out of operation at a time. Each delivery pump 4 is connected to the two reservoirs 3 by a branchpipe 90.. By remote-controlled cocks H each reservoir can be connected by a branch of the suction pipe to a delivery pump. An air separator 90, shown in Fig. 6, is connected by the union I8 to the common pressure pipe 5 of the two delivery pumps. This construction of the air separator differs in construction and operation from the examples already described by the feature that the casing of the air separator He is divided by a partition wall 99 into two chambers 91 serving for the separation of the air carried with it by the fuel, while the chamber 98 is provided for the separation of particles of fuel which may still adhere to the air conveyed into this chamber. The fuel freed from air is conveyed from the first chamber 91 through the union I5 and the pipe I to the injection pump. The air freed from fuel in the chamber 98 passes from the centre of the air separator through the union I4 and the pipe IM to the induction pipe S of the engine, while the fuel separated from the air in the chamber 98 is led away through a union 99 and the pipe 1a to the overflow pipe, which conveys the suction pipe 4a of the delivery pump.

The rotatable member I99 arranged in the chamber 91 is mounted at one side in the partition wall 99 and at the other side in the cover I9I of this chamber. A radial bore I92 is arranged in the partition wall between the two chambers, and is connected at one end to the feed pipe 5, and at the other end 'opens into an annular space I93 provided on the rotatable member and open towards the partition wall 99,

ready described. If the delivery pumps deliver fuel containing air or bubbles, the gases collect the chamber and flow I99 into the pipe I91 I98 in the axis of the rotatable member and then pass to the chamber 99 through a bore I99 going through the partition wall 99.

In the chamber 98 a rotatable member H9 is also arranged, the journals of which are mounted at one side in an opening in the partition wall 89 and at the other side in a cover II I which externally closes this space. A pendulum II2 flxed to the rotatable member II9 tends to adjust the rotatable member always into approximately the same position relative to the outer space. A sleeve I I8 is inserted over the rotatable member, and can turn relative to-the rotatable member, and containstwo opposite radial bores staggered relative to each other in the longitudinal direction. To the bore situated at the top in the drawings a pipe I is connected, and this pipe is surrounded by a float H5. which is fastened to the sleeve.

in the upper part of through the cross pipe and 98, the chamber 91 p it back to i In the same radial plane in which the said upper bore opens into the running surface of the sleeve a radial bore I I6 is provided in the rotatable member H0 and opens into a longitudinal bore II! in the axis of the rotatable member. The longitudinal bore II'I terminates at the end of the journal of the rotatable member that is mounted in the partition wall 96 in a space that is connected by a passage I I8 in the partition wall to the air discharge pipe Illa. In the passage II8 there is a throttle I20.

In the bore of the sleeve that is situated at the bottom in the drawings a pipe I 2I is fixed, whose free end thus projects into the internal space of the chamber 98 in an opposite direction to the pipe I. In the radial plane of this pipe a radial bore I22 is arranged in the axis of the rotatable member, and merges into a longitudinal bore I23 opening out at the cover side. A union 99 is screwed into the boss of this cover, and connects the pipe Ia and thus the overflow pipe 5a of the delivery pump to the air separator. In the longitudinal bore I23 there is also a throttle I 24, which throttles the passage of the fuel passing through the pipe I2I and the longitudinal bore I23. Several grooves I25 turned in the axis of the rotary member are connected by a longitudinal groove in the rotatable member to a sealing oil pipe I26 connected to the boss of the cover.

Air or fuel passes from the chamber 91 through the cross pipe I06, pipe I01 and the bore I08 and I09 into the chamber 98. Air bubbles separate therein from the fuel. When the level of the fuel is low, the float is rocked downward, as shown in Fig. 7, while the opening of the airdischarge pipe H4 surrounded by the float always stands higher than the level of the fuel. When a certain level is reached the air discharge pipe H4 is connected to the bore H6 and the longitudinal bore II1 of the rotatable member, so that the air can escape through the bore H8, H9 and I20 to the union .I4, and from this through the pipe Illa to the induction pipe of the engine. The pipe I2I does not dip into the fuel in this position of the float, and the sleeve closes the bore I22 for the discharge of fuel to the pipe Ia.

As soon as the fuel has risen above a predetermined level (Fig. 8), the sleeve rotated by the float closes the bore II 6, also on a further rise of the level, the air discharge pipe In remains constantly shut off from the chamber. For this, the pipe I2I clips on the further rotation of the bush into the fuel level, and when it comes into register with the bore I22, fuel flows away through the longitudinal bore I23, throttle I24, and the union, through the pipe 1a to the suction side of the delivery pump. In this example of construction, the passage of fuelfree air and air-free fuel to the discharge pipes is so throttled by the throttles I 20 and I 24 respectively, that the opening of these discharge pipes cannot lead to a sinking of the pressure in the first chamber of the air separator, and thus in the suction chamber of the injection pump, below the desired pressure.

We; declare that what we claim is:

1. An air separator for fuel-pumping apparatus for aircraft or other internal combustion engines that are variable in position comprising a casing provided with an inlet for fuel under pressure, an

outlet for fuel under pressure and an outlet for air, means rotatably mounted in said casing and provided with radially-extending passages having inlets adjacent a peripheral wall and opening into the interior of said casing, one of said passages being connected to said fuel outlet and the other being connected to said air outlet, means carried by said rotatable means for maintaining the same in such a position that the inlet end of the fuel passage of said rotatable means is always in the lower portion of said casing and the inlet end of the air passage of said rotatable means is always in the upper portion of said casing in any position of said casing about its axis, and floatcontrolled means carried by said rotatable means for automatically closing said air passage as soon as a predetermined fuel level has been reached in said casing.

2. An air separator for fuel-pumping apparatus for aircraft or other internal combustion engines that are variable in position comprising a casing provided with an inlet for fuel under pressure, an outlet for fuel under pressure and a restricted outlet for air, means rotatably mounted in said casing and provided with radially-extending nassages terminating adjacent a peripheral wall and opening into the interior of said casing, one of said passages being connected to said fuel inlet, another passage being connected to said fuel outlet and another passage being connected to said air outlet, means carried by said rotatable means for maintaining the same in such a position that the inlet end of the fuel outlet passage of said rotatable means is in the lower portion of said casing and the inlet end of the air outlet passage relative to said rotatable means and automatically closing the inlet end of said air outlet passage when a predetermined fuel level has been reached in said casing.

3. An air separator as set out in claim 1 in which the casing iscylindrical and the rotatable in the center of an end wall of the casing.

4. An air separator as set out in claim 1 in which the casing is provided with axial hollow bearings forming the outlet for fuel and the outlet for air respectively of said casing, the rotatable with longitudinally extending passages which register, respectively, with the radially extending passages in said rotatable means, and the outlet for fuel and the outlet for air provided by said hollow bearings.

5. An air separator as set out in claim 1 in which the float controlled means includes a float memoer radially guided on said rotatable means, and a valve in said air passage and controlled by said float member, said valve being closed and opened by radial movement of said float member relative to said rotatable means.

WILLY VOIT. J OHANN FRIEDRICH J ANSSEN 

